Electro-mechanical transducer



Dec. 12, 1961 l v. A. BERNIER 3,013,189

ELECTRO-MECHANICAL TRANSDUCER Filed Sept. l0, 1959 2 Sheets-Shea?l 1 [38w 4f 24 l 4 l V/\///| 7/ N \1,

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ELECTRO-MECHANICAL TRANSDUCER Filed Sept. 10, 1959 2 Sheets-Sheet 2 IN VEN TOR.

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United States Patent O 3,013,189 ELECTRO-MECHANICAL TRANSDUCER VaughanA. Bernier, Kankakee, Ill.

(505 Coralina Ave., Clinton, N.C.) Filed Sept. 10, 1959, Ser. No.839,185 8 Claims. (Cl. 317-173) This invention relates to anelectro-mechanical transducer, and has for one purpose the provision ofmeans for transforming variations in an electrical signal intomechanical movement.

Another purpose is an electro-mechanical transducer which may be used ona loud speaker unit.

Another purpose is an electro-mechanical transducer which can changeelectrical energy into mechanical movement or mechanical movement intoelectrical energy.

Another purpose is an electro-mechanical transducer having improvedoperating characteristics, and wlhen used in a speaker unit eliminatesthe necessity of coupling transformers.

Another purpose is a method of transforming electrical signal variationsinto corresponding mechanical variations in which the permanent orbiasing field comprises two elds of energy having parallel lines of fiuxbut opposite polarity.

Another purpose is an electro-mechanical transducer having two generallyconstant opposed parallel fields which may be modulated by a third fieldsuch that when one field increases, the other decreases.

Another purpose is to provide a sound reproducing unit having twoopposing fields impressed on the armature thereof.

Other purposes will appear in the ensuing specification, drawings andclaims.

The invention is illustrated diagrammatically in the following drawingswherein:

FIGURE l is a Vertical section of my improved electro-mechanicaltransducer,

FIGURE 2 is a horizontal section taken along line 2-2 of FIGURE 1,

FIGURE 3 is a vertical section of a variant form of myelectro-mechanical transducer, and

vFIGURE 4 is a vertical section of a further form of electro-mechanicaltransducer embodying the principles disclosed herein.

Referring now to FIGURES l and 2, a generally cylindrical non-magnetichousing has a bottom wall 12, as shown in the drawings, and a top wall14 having a generally central aperture or opening 16 therein. The bottomwall 12 has a central upwardly projecting portion 18 upon which ispositioned a permanent magnet 20, suitably bonded to the portion 18. Asecond permanent magnet 22 is positioned above the magnet 20 and issimilarly bonded thereto to provide a rigid strong structure.

lThe direction of the magnetic fields or the polarity of the twopermanent magnets and 22 should be so arranged that either the twonorthpoles or the two south poles are positioned adjacent each other atthe point where the magnets are bonded together. Two magnetic fieldswill therefore be formed by the permanent magnets which will have linesof flux that are generally parallel but of opposite polarity.

A suitable electric coil 24, which is connected to coil leads 26 and 28extending through small holes 30 and 32 Vrespectively in the wall of thehousing, is positioned outside of the permanent magnets and adjacent thenon-magnetic housing wall. The magnets and the coil 24 define agenerally annular chamber or space 34. ln the chamber or space 34 is agenerally cylindrical driving element or armature 36 extending generallythroughout the length Yof the chamber and formed of a suitable magneticmaterial having high permeability. The armature has an axial slot oropening 37 running throughout the length thereof which prevents shortingof the magnetic fields formed therein. Attached to the armature is acylindrical connecting element or connecting tube 38 which is formed ofa suitable non-magnetic material. The upper portion of the connectingelement 38 is suitably connected to a pair of spaced generally annulardiaphragme or support members 40 and 42. Whereas I have shown twodiaphragms, it should be understood that one may be sufficient. Thediaphragms or support members may be corrugated, such as shown in thedrawings, or they may be otherwise, as the particular shape of thediaphragms or support members is not essential to the invention. It isimportant however, that the diaphragms or support members be generallyflexible so that they will support the connecting element and thearmature or driving element but yet permit movement of these elements ina generally vertical path or in a path generally parallel to themagnetic field.

In the operation of the device shown in FGURES l and 2, there are twogenerally constant magnetic fields formed by the two permanent magnets.These fields are of opposite polarity and have generally parallel linesof fiux. The strength of the two magnets may be the same or they mayvary one from the other, the important thing is that they be opposite.When an electric signal is applied to the coil leads, a magnetic fieldwill be formed in the coil due to this electric signal. Since it is thepurpose of my invention to provide a means to allow movement of theconnecting element in response to variations in the electric signal, thesignal supplied to the coil will usually be a variable signal. As thissignal varies, the polarity, frequency and relative strength of thefield fromed at opposite points on the coil will change. When, forexample, the electrical signal has a polarity and strength such that theupper portion, as shown in the drawings, of the coil takes on a northpolarity and the bottom portion of the coil takes on a south polarity,the strength of the field in the coil due to the electric signal willadd to the strength of the field formed by the top magnet and willsubtract from the strength of the field formed by the bottom permanentmagnet. Therefore the armature and the connecting element will moveupward, as shown in the drawings. When the polarity of the field formedin the coil reverses there will be reverse movement of the drivingelement and connecting element. As the strength of the field formed inthe coil varies according to the strength and frequency of the electricsignal the amplitude and rate of movement of the connecting element anddriving element will vary. With no signal applied to the coil, theopposite fields will hold the armature in one position, generallyintermediate the ends of the magnets. For convenience I may refer to therelatively constant field formed by the center magnets as the biasingfields and the field formed by the coil and the electric signal as themodulating field.

Referring now to FIGURE 3, wherein parts common to the FIGURE l and 2forms are indicated by like numerals, the only difference from thestructure shown in FIG- URES 1 and 2 is that instead of lusing a pair ofpermanent magnets to establish my biasing fields I have provided anelectro-magnet. The electro-magnet comprises an upper coil 44 and alower coil 46 suitably wound on a core element 48. The coils are fedthrough suitable coil leads 50 and 52 which reach the coils throughsuitable holes 54 and 56 in the non-magnetic housing 10 and the core 48.The coils are connected together by a suitable lead S8. The coils shownin FIGURE 3 should be so wound that the magnetic fields establishedthereby'are similar to the magnetic fields of FIGURES l and 2. In otherwords, the magnetic fields should provide lines of notarse flux whichare generally parallel but of opposite direction or polarity. Theoperation of the device shown in FIG- URE 3 is substantially similar tothat shown in FIGURES l and 2, however in this case, the biasing orrelatively constant fields are formed by the electro-magnet rather thanby the permanent magnets. As was the case in the forni of FEGURES l and2, the magnetic field formed in the coil 24 will add to one of thebiasing magnetic fields while subtracting from the opposite field so asto provide additional attracting force and so movement of the armatureand connecting element in the chamber 34.

i have shown a further form of my invention in FIG- URE 4 wherein likeparts are again indicated by like numerals. In this form of theinvention, instead of providing a pair of magnetic fields havingopposite polarity, l have provided two electric fields, again ofopposite polarity. Batteries or other suitable sources of direct currenttitl and 62 are so wired that like terminals, and in this case thenegative terminals, are common. The electric fields or electro-staticfields are formed by suitable conductors, which may be in the form ofannular rings or the like. The-re is an upper electric field and a lowerelectric field, both parallel, and having opposite polarity. The upperfield may be formed by an. outer ring 54, which has a positive charge asit is connected to the positive terminal of the battery 6h, and a spacedlower outer ring do connected to the opposite side of the battery and sohaving a negative charge. The upper electric field is completed by aninner ring 68 having a positive charge and a lower inner ring 7@ havinga negative charge. Wire 69 connects outer ring 64 and inner ring 68 andwire 71 connects outer ring 66 with inner ring 70. The lower electricfield, which has opposite polarity, is formed by `outer and inner rings66 and 70 and outer and inner rings 74 and 76 which have a positivecharge. Wire 73 connects rings or conductors 74 and 76. The housing 10has an upwardly projecting center portion 72 upon which the inner ringsare positioned and which in the preferred form should be formed of anon-magnetic material. I have placed suitable spacer elements 75adjacent each of the annular rings or conductors to provide a largerarea or surface for the electric charge. The elements 75 may be of thesame material as the annular conductors or they may be otherwise. Theaction of the electric fields formed by the annular conductors issimilar to that of a capacitor in that I have provided longitudinallyspaced surfaces or plates having opposite charge or polarity. Thesespaced, oppositely charged surfaces will provide electric fields, whichfields, as shown in the drawings, will be parallel and of oppositedirection. The fields will be generally parallel to the connectingelement 3S or generally parallel to the outwardy projecting centerportion 72.

The connecting element or connecting tube 38 has upper and lowerconductor elements 78 and 80. Each of these conductor elements mayreceive an electric signal through suitable wires 82 and 84, so that anelectric field will be set up between the elements 78 and 80'. Thiselectric field will be similar to a capacitor type action in that thereare two oppositely charged plates or surfaces spaced from each other.The electric field will be generally parallel to the biasing fieldsformed by the ring elements. In this for-m of the invention theoperation is similar to that described before in that the electric fieldformed on the connecting element, or the modulating field, will eitheradd to or subtract from each of the more constant or biasing electricfields and so cause movement of the connecting element in a pathgenerally parallel to the electric fields.

Use, operation and function `of the invention are as follows:

The electro-mechanical transducer shown and described herein may haveparticular application to sound reproducing units or loud speakers.There are however many other applications for the device Iand method,such as in recording devices, for example, in cutters and galvanometers.It also has use in positioning units and in any other type of assemblywherein it is desired to transform either variation in mechanical motioninto variations in an electrical signal or the reverse.

The description of the invention has been directed to a device whereinvariations in amplitude and frequency of an electrical signal applied tothe coil or to the elements 73 and fifi caused corresponding mechanicalmovement of a connecting member or element. it should be understoodhowever, that my invention also includes a device wherein mechanicalmovement of the armature or driving element will cause variations in thelines of flux passing through the coil and so induce a signal in thecoil having a frequency and amplitude proportional to the movement ofthe armature. The device shown herein is equally suitable for eithertype of operation, and its description as changing electrical variationsto mechanical is merely for purposes of illustration.

My invention, regardless of which form, operates on a general principlewherein two fields of energy which are relatively constant, and producelines of flux which are generally parallel and of opposite polarity, areeither decreased or increased by the variations of a third field ofenergy which has lines of liuX generally parallel to the constant orbiasing fields. The biasing fields oppose each other with parallel linesof flux. The modulating field lwill add to the strength of one of thebiasing fields and subtract from the strength of the other. The increasein the strength of one field will provide a stronger attraction ordriving force for the armature or other driving member spaced betweenthe fields. Thus the diving element will have movement corresponding tothe variations in the strength and frequency of the modulating fieldwhich may be varied by a suitable electric signal.

When the device is being used to change mechanical movement into anelectrical signal, the movement of the armature along the parallel linesof flux of the two biasing fields will vary the strength of the fieldinduced in the coil Iby the biasing fields. Thus an electrical signalwill be produced in the coil which will correspond to the mecham'calmovement of the armature.

In one form of the invention both the modulating and the biasing fieldsare magnetic fields and I have placed an armature having highpermeability between the biasing and modulating fields. This armature ismoved in a path generally parallel to the fiuX lines and moves accordingto variations in strength and frequency of the modulating field.

In one form of magnetic electro-mechanical transducer, I have used twopermanent magnets positioned so that either both north poles or bothsouth poles are adjacent each other whereby I have two fields ofopposite polarity. In the other form of magnetic transducer my biasingfield is formed by electromagnets. I have a core upon which are woundtwo coils. The coils being so connected that I form magnetic fields ofopposite polarity.

In the third form of the invention I provide electric or electrostaticfields by placing oppositely charged surfaces longitudinally spacedfrorn each other. An electric field will be established between theseoppositely charged surfaces, much like in a capacitor. These electricalfields will be generally parallel to the connecting element. Instead ofa coil such as I have used in the magnetic forms to establish myvariable fields, I have opposite charged surfaces spaced longitudinallyof each other and so positioned that they may either add to or subtractfrom the strength of the more constant or biasing electric fields. Thechange on these surfaces is supplied by an electric signal which mayvary both in polarity, frcquency and amplitude such as a voice signal.These variations will vary the strength of the opposed biasingelectrical fields which in turn will cause corresponding movement of theconnecting element.

There are many modifications, substitutions and alteraltions which maybe made to the invention without departaclaran ing from the scope of thefollowing claims. For example, I have shown a generally cylindricalconstruction for my transducer. It should be realized however that theparticular shape of the members herein is not essential. Nor is itessential that the polarity of the fields be as shown in the drawings,as it is only essential that the polarity be opposite so that the fieldsoppose each other. Additionally, although I show the biasing fields asbeing parallel, It is possible to have the fields formed at a slightangle Without departing from the scope of the invention. I may make afurther modification to my invention by reversing the placement of thecoil and constant magnetic afield and have the coil within the armatureand the constant field on the outside. Either form is satisfactory.

I claim:

1. An electro-mechanical transducer including a diaphragm, a connectingelement supported thereby, a driving element connected to saidconnecting element, means for producing two generally constant fieldsor" energy so positioned that the lines of flux produced thereby aregenerally parallel but with opposite polarity, means for producing athird iield of energy, the flux lines of said third ield being generallyadjacent and parallel to the flux lines of said generally constantfields of energy, said driving element and connecting element beingpositioned between said constant fields of energy and said third iieldof energy, means for varying said third named iield of energy tosimultaneously vary said constant fields of energy in oppositedirections, said driving element being responsive to said variations inthe eld strengths whereby said connecting element is moved in a pathgenerally parallel to said flux lines.

2. The structure of claim l wherein said fields of energy are magneticfields.

3. The structure of claim l wherein said fields of energy are electricfields.

4. An electro-mechanical Vtransducer including a diaphragm, a generallycylindrical connecting element supported thereby, an armature positionedon said connecting element, means for producing two generally constantmagnetic fields on one side of said core element, said magnetic fieldsbeing so positioned that the lines of flux produced thereby aregenerally parallel, but of opposite polarity, means for producing athird magnetic iield on the opposite side of said core element, saidthird magnetic field having lines of iiux parallel to said generallyconstant tiux lines and parallel to said armature, means for varyingsaid third magnetic lield to simultaneously increase one of saidgenerally constant fields and decrease the other to thereby move saidarmature in a path generally parallel to said magnetic lines of flux.

5. The structure of claim 4 wherein said constant magnetic iields arepositioned within said connecting element and armature, and said thirdmagnetic field surround said connecting element and armature.

6. The structure of claim 5 wherein the means for producing saidconstant magnetic fields includes a pair of permanent magnets positionedwith like poles adjacent each other.

7. The structure of claim 5 wherein the means for producing the constantmagnetic fields includes an electromagnet.

8. An electro-mechanical transducer including a diaphragm, a generallycylindrical connecting element Supported by said diaphragm, a generallycylindrical armature connected to said connecting element, a pair ofpermanent magnets positioned one on top of the other inside of saidarmature, the magnetic elds formed by said magnets being generally equaland of opposite polarity, and a coil positioned outside of said armaturesuch that the magnetic eld produced thereby will be generally parallelto the magnetic fields of said magnets.

References Cited in the file of this patent UNITED STATES PATENTS

